Generally, the most relevant prior art is found in, application, PCT/CA2008/000667, filed 14 Apr. 2008, publication WO/2008/124925, published 23 Oct. 2008, Prystupa et al. The document discloses a device to detect infected kernels, which had an LED passing light through a collimator consisting of a glass rod about 3 mm diameter and 4 cm long with a 5 mm sphere on its end acting as a focussing lens onto a kernel approximately 6 mm from the sphere. A light receiving device consisted of an array of optical fibre bundles spaced from and surrounding the sphere subtending an inner angle of about 30° from the rod axis and an outer angle of about 60° from the rod axis at the kernel. The optical fibre bundles combined the collected light at a photodiode. This arrangement satisfactorily distinguished infected from healthy kernels by analysis and comparison of reflected light intensity, in practice measuring the kernel shadow was used for normalisation.